The research investigates the relationship between subjective sense of intoxication and blood alcohol concentration in order to determine the characteristics of adaptation to ethanol that may describe a continuum of drinkers, from moderate users to severe abusers, and that may help to identify potential abusers. We will test the hypothesis that abusive drinkers, or potential abusers who now drink normally, more rapidly adapt to subjective feelings of intoxication than do normal drinkers. Measures of subjective effects will be validated with a number of other techniques, including ad lib drinking measures, a "taste-test" measure of consumption of alcohol, drinking profiles, memory for pictures, and measures of "need" for another drink. If the test we develop is reliable and valid in assessing degree of alcohol abuse, it may be helpful in objectively deciding on the appropriateness of moderation as a treatment goal for some abusers. The other major benefit to public health is that the test may facilitate primary prevention among moderate drinkers. Drinkers without a history of abuse, but who nonetheless are very insensitive to lower blood alcohol levels, could be forewarned of their potential for developing abusive drinking habits.